FIG. 37 is a perspective view showing a mold set used for forming an exterior packaging body of a conventional resin molded capacitor. Mold set 120 for resin-molding includes upper mold 121 and lower mold 122. Upper mold 121 is provided with gate 123 through which an uncured resin is injected. Further, upper mold 121 and lower mold 122 are provided with air vent hole 124 in mating surfaces thereof for removing air when injecting a resin.
In order to mold the exterior packaging body, first, capacitor element 126 to which clasps 125 are connected is placed on lower mold 122. At this time, capacitor element 126 can be accurately positioned in lower mold 122 by fitting clasps 125 into recesses 127 in lower mold 122.
Next, upper mold 121 is fastened to lower mold 122, and an uncured resin is injected through gate 123. As the resin, it is preferable to use a norbornene based resin. As the norbornene based resin can be cured in a short period of time, it is possible to manufacture a resin molded capacitor with excellent productivity. It is preferable that temperatures of upper mold 121 and lower mold 122 are within a range from 50° C. to 120° C. such that a curing reaction of the norbornene based resin progresses.
Thereafter, mold set 120 is opened, and, as shown in FIG. 38, resin molded capacitor 129 is produced over which exterior packaging body 128 is molded. Such a technique is disclosed in Patent Document 1, for example.
As described above, the norbornene based resin yields high productivity as it is cured in a short period of time. However, there is often a case in which the norbornene based resin is cured before it is sufficiently filled into a cavity defined by upper mold 121 and lower mold 122, as the curing speed of the norbornene based resin is too fast. Consequently, manufactured resin molded capacitor 129 often includes a portion that is not covered sufficiently by exterior packaging body 128, possibly resulting in reduced reliability.